In recent years, the 3GPP (3rd Generation Partnership Projects) has proposed and specified a mobile communication system employing a communication method called either a “W-CDMA (Wideband-Code Division Multiple Access) method or a “UMTS (Universal Mobile Telecommunications System) method” based on Code Division Multiple Access (CDMA) techniques.
FIG. 8 shows a configuration example of a mobile communication system of the W-CDMA mode. As shown in FIG. 8, the mobile communication system of the W-CDMA mode includes a mobile station UE (User Equipment), radio base stations NodeB, a radio network controller RNC, and an exchange station MSC/SGSN (Mobile Switching Center/Serving GPRS Support Node), thereby constituting the mobile communication system of a cellular method.
In the above-described mobile communication system of the W-CDMA method, an area called a “cell” that constitutes a control unit in the cellular method is formed by a radio wave delivered by the radio base station NodeB. This area is also called a “sector” when the area is formed into a sector by a directional antenna.
Here, it is usual that there are multiple radio network controllers RNCs and multiple exchange stations MSCs/SGSNs connected to one another because the exchange stations are arranged in a hierarchy. However, only one radio network controller RNC and one exchange station MSC/SGSN are shown in this description for simplification.
Moreover, it is usual to install a device called a home memory configured to store subscriber information, a server for offering application services, and the like in addition to the exchange station MSC/SGSN. However, description thereof will be omitted in this description similarly for simplification on the assumption that the function of the home memory and the function of the server are included in the exchange station MSC/SGSN.
Meanwhile, as for the type of the radio base station NodeB, it is considered to introduce a subminiature radio base station (hereinafter a femto radio base station) for mainly covering a small space such as an indoor space besides a radio base station having a relatively large capacity for widely covering an outdoor space.
Here, a cell formed by the outdoor radio base station is called a “macrocell” and a cell formed by the femto radio base station is called a “femtocell”.
These femto radio base stations are each usually configured to include an IP interface for connection to the radio network controller RNC, and are technically capable of using a broadband network for home as a network for connection to the radio network controller RNC.
Moreover, the femto radio base station is generally small in size and low in price but has a structure supporting automatic adjustment of radio parameters corresponding to installation conditions. For this reason, it is possible to implement an operation mode allowing a general user to install the femto radio station readily and freely by connecting the femto radio station to an existing broadband network.
In the designing of the mobile communication system of the W-CDMA method, there may be a necessity to implement a function to perform control depending on a location of a mobile station UE in communication (that is, a communication-location dependent control function) as control specific to the mobile communication system.
For example, this is the control to connect the mobile station UE to an emergency agency closest to an area where the mobile station UE is in communication at the time of emergency notification, or to distribute restaurant information, weather information or the like near a location where the mobile station UE is present to the mobile station UE.
As a method of implementing the above-described communication-location dependent control function, there are methods of employing a “SAI (Service Area Identifier)” and a “Geographical Area Identifier (hereinafter GAI)” defined in the standard specification of the W-CDMA method.
The “SAI” is an information element in the 3GPP standard specification, which is formed as a combination of a “PLMN-ID (Public Land Mobile Network Identifier)”, a “LAC (Location Area Code)”, and a “SAC (Service Area Code)”.
The “PLMN-ID” is an identifier for uniquely identifying a carrier which offers a mobile communication service. The “LAC” is an identifier for uniquely identifying a location registration area in the mobile communication system of the carrier. The “SAC” is an identifier for specifying a segmented area in the location registration area.
Although the configuration of the “SAC” can be determined as needed under the 3GPP standard specification, the “SAC” may include a unique radio network controller number within the “LAC”, a unique radio base station number within the radio network controller, a unique cell number (or sector number, if formed into a sector by the directional antenna) within the radio base station, and the like.
In the meantime, although the “GAI” is also an information element in the 3GPP standard specification, the “GAT” is absolute geographic information independent of the configuration of the mobile communication system, that is, information containing latitude and longitude information.
In an example shown in FIG. 9, in a station configuration table retained by a radio network controller RNC01, “AA” is written as “PLMN-ID+LAC”, “01” is written as “RNC number=01”, “01” and “02” are written as “NodeB numbers” under the radio network controller RNC01 specified by “RNC number=01”, and “01” and “02” are written as “sector numbers” under each of radio base stations NodeB01 and NodeB02 respectively specified by the “NodeB number=01” and “NodeB number=02”.
The “SAT” for respective cells are “AA010101”, “AA010102”, “AA010201”, and “AA010202” in order from the top.
Meanwhile, the latitude and longitude information on each of the cells is written as the “GAI”.
In the meantime, the exchange station MSC/SGSN retains address information (such as a telephone number) of an emergency agency in association with the “SAI”. For example, if there are an emergency agency 1 and an emergency agency 2 having the address information of “XXX1” and “YYY1”, respectively, around the cell having the “SAT” of “AA010101”, the exchange station MSC/SGSN stores the “SAT=AA010101” and the emergency agencies 1 and 2 in a destination table in association with each other.
The exchange station MSC/SGSN is notified of the “SAT” and the “GAT” by the radio network controller RNC by using “RANAP (Radio Access Network Application Part)” which is a signaling protocol in an application layer between the radio network controller RNC and the exchange station MSC/SGSN.
The exchange station MSC/SGSN retains the associations between the address information of the emergency agencies and the “SAI” in the destination table. Upon receiving a communication start request for emergency notification from the cell specified by the “SAI”, the exchange station MSC/SGSN figures out the address information of the emergency agencies from the “SAI” notified by the radio network controller RNC in advance and transfers the communication start request to the address information of the emergency agencies.
Meanwhile, the above-described mobile communication system is able to offer a service of providing the mobile station UE with the longitude and latitude information included in the “GAI” and causing an application of the mobile station UE to display a screen of the nearest restaurant information or the weather information at the location specified by the “GAI”, and to offer a service of providing the emergency agency with the longitude and latitude information included in the “GAI” so as to specify the location of the mobile station UE carrying out the emergency notification.
FIG. 10 shows operations of the conventional mobile communication system.
As shown in FIG. 10, in step S3001, the mobile station UE transmits a connection request for carrying out emergency notification communication addressed to the emergency agency 1 to the radio network controller RNC01.
In step S3002, the radio network controller RNC01 transmits a radio link establishment request to the radio base station NodeB01. In step S3003, the radio base station NodeB01 transmits a radio link establishment response to the radio network controller RNC01. In step S3004, a radio link establishment procedure is performed by the mobile station UE and the radio network controller RNC01.
In step S3005, the mobile station UE transmits a service request for carrying out the emergency notification communication addressed to the emergency agency 1 to the radio network controller RNC01 via the radio network established in step S3004.
In step S3006, with reference to the station configuration table, the radio network controller RNC01 extracts the “SAI” of the cell in which the mobile station UE is in communication, and transmits a service request including the “SAI” to the exchange station MSC/SGSN. The exchange station MSC/SGSN stores the “SAI”.
After security and authentication procedures are performed by the mobile station UE and the exchange station MSC/SGSN in step S3007, the mobile station UE transmits a setup signal to the exchange station MSC/SGSN in step S3008. Here, the setup signal is for carrying out the emergency notification communication addressed to the emergency agency 1, more specifically, the setup signal includes “XXX” that means to carry out the emergency notification communication addressed to the emergency agency 1.
In step S3009, when the exchange station MSC/SGSN recognizes the “XXX” included in the received setup signal, the exchange station MSC/SGSN searches the destination table while using the “SAI” stored in step S3006 as key information to acquire the address information “XXX1” of the emergency agency 1, and transfers the setup signal to the address information “XXX1” of the emergency agency 1.
In step S3010, the communication (the emergency notification communication) between the mobile station UE and the emergency agency 1 is started after alerting and response procedures. Then, in step S3011, the emergency agency 1 transmits a location information request including the above-described “SAI” to the radio network controller RNC via the exchange station MSC/SGSN. In step S3012, the radio network controller RNC returns the “GAI”, which is extracted by searching the station configuration table by using the “SAI” as key information, to the emergency agency 1 via the exchange station MSC/SGSN.
Here, the station configuration table and the destination table described above are statically retained in memories or disks as part of system data of the radio network controller RNC and the exchange station MSC/SGSN, respectively.
In a common practice for responding to changes in operating conditions, these system data are usually created as a file periodically, for example, once every week by a maintenance worker using a dedicated software tool, and inputted into the radio network controller RNC and the exchange station MSC/SGSN to be expanded into the memories and the disks.
Among the “PLMN-ID”, the “LAC”, as well as the radio network controller numbers, the radio base station numbers and the selector numbers in the “LAC” constituting the “SAI”, the “PLMN-ID” is normally unchanged but the “LAC”, the radio network controller numbers, the radio base station numbers, and the selector numbers may be changed during the operation due to a change in the location registration area, a new installation or connection change of the radio network controller RNC or the radio base station NodeB, and so forth.
In that case, it is necessary to change the station configuration table in the radio network controller RNC and the destination table in the exchange station MSC/SGSN synchronously in accordance with the above-described procedure.